Polynucleotide detection and analysis is becoming increasingly important in many research, medical, and industrial fields, e.g. Caskey, Science 236: 1223-1228 (1987); Landegren et al, Science, 242:229-237 (1988); and Arnheim et al, Ann. Rev. Biochem., 61: 131-156 (1992). Several techniques have been developed which exploit the specific hybridization of a probe nucleic acid to a complementary target nucleic acid for detection of the target. Generally, the most powerful of such techniques involve some form of target sequence and/or signal amplification, e.g. polymerase chain reaction, Arnheim et al (cited above); ligation-based amplification, e.g. Barany, PCR Methods and Applications 1: 5-16 (1991); strand-displacement amplification, Walker et al, Proc. Natl. Acad. Sci., 89:392-396 (1992); branched probe signal amplification, Wang et al, U.S. Pat. No. 4,925,785, Urdea et al, U.S. Pat. No. 5,124,246, Hudson et al, J. Am. Chem. Soc., 115:2119-2124 (1993); and the like.
In regard to the latter catagory of techniques, synthesis of the branched probe structures by current methods is typically difficult, results in low yields, and provides only limited and indirect means for monitoring yield and product quality during and after synthesis. Presently, most branched polymer approaches to polynucleotide detection do not lend themselves to the production of practical commercial assays.